1. Field of the Invention
The present invention relates to a voltage converting apparatus. More particularly, the present invention relates to a voltage converting apparatus with auto-adjusting boost multiple.
2. Description of Related Art
The voltage converting apparatus is a necessary interface circuit between circuits with different operating voltages. For example, the voltage converting apparatus is one of the important components for the thin film transistor liquid crystal display (TFT LCD). Because each of the function blocks in the TFT LCD operates in different operation voltage, the TFT LCD must utilize the voltage converting apparatus to generate the operation voltage required by each of function blocks, for example, the function blocks include the gate driver, source driver and timing controller.
FIG. 1 is an architecture diagram of the conventional voltage converting apparatus. As shown in FIG. 3, the conventional voltage converting apparatus 100 converts the input voltage VIN to the output voltage Vout1 according to the digital signal SD1. In the process of converting the input voltage VIN to the output voltage Vout1, a conventional microprocessor unit 101, fist according to the digital signal SD1, produces the converting multiple information ST1 for amplifying the output voltage Vout1. The conventional boost unit 130 produces the converting operation voltage VTP1 through a fixed boost multiple. Therefore, conventional voltage converting unit 140 is operated between the converting operation voltage VTP1 and a ground voltage. According to the converting multiple information ST1, the conventional voltage converting unit 140 amplifies the reference voltage Vref1, which is produced by the conventional reference voltage generating unit 120, and converts it to the output voltage Vout1.
For example, when the single operation voltage of TFT LCD is 2.4V, and the operation voltages of the function blocks are individually 8V, 6.5V, and 4V, the converting operation voltage VPT1 generated by the conventional boost unit 130 must be larger than 8V. For example, through four times of the boost multiple, the conventional boost unit 130 produces the converting operation voltage VPT1 which is 9.6V. In this way, according to the converting multiple information ST1, the conventional voltage converting unit 140 can produce the output voltages VOUT1, which are 8V, 6.5V, and 4V.
However, because the conventional boost unit 130 produces the converting operation voltage VPT1 only through the fixed boost multiple, the conventional voltage converting unit 140 must be operated in the 9.6V converting operation voltage VPT1 even though the conventional voltage converting unit 140 only needs to produce the 4V output voltage VOUT1. In other words, the conventional voltage converting apparatus 100 not only lacks flexible application but also has greater power consumption.